Re; need help for the transformation

Chris LaRosa clarosa at
Wed Aug 30 14:41:41 EST 2000

> When co-transformants are a problem, pick the original colony and restreak
> it onto a daughter plate.  The 12-15 generations required to generate new
> colonies will allow segregation to occur and will reduce the number of
> co-transformants to a more manageable level (perhaps 1 out of 50 colonies).
> The daughter colonies should be inoculated into 3 mL of liquid culture (to
> allow more segregation) for plasmid prep and sequencing.
Years ago when a professor taught me to clone, he taught to always
restreak the single colonies from a primary selection plate.   The
stated reason was to get rid of any untransformed bacteria, but the off
chance of hetererozygotes or co-transformation described in this thread
is a good reason to always restreak before sequenceing, subcloning..

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